Sterilization is a process conducted in a specially designed chamber or sterilizer that results in a complete eradication of all viable microorganisms. Sterilization techniques have evolved over time from the traditional methods employing saturated steam at elevated temperature and ethylene oxide gases to more modern techniques, such as those employing liquid, vapor and plasma. Regardless of the technique utilized, the effectiveness of the applied sterilization process must be evaluated especially when sterilizing instruments and devices invasive to the human body.
So-called biological indicators are devices that are used to test the efficacy of sterilization processes. Typically, a biological indicator is placed within a sterilization chamber during a sterilization process. The biological indicator system includes a source of microorganisms, a culture medium, and a visible detector to indicate the presence or absence of viable microorganisms. The source of microorganisms is typically an absorbent paper strip that has been impregnated with a pre-determined concentration of viable microorganisms. After the biological indicator has been subjected to the sterilization process, the microorganism-impregnated strip is exposed to the sterile culture medium, and incubated for a predetermined time at an appropriate temperature. At the end of the incubation period, the indicator is evaluated either visually or with a detector to determine whether any microorganisms survived the sterilization process.
The present invention provides a self-contained biological indicator for determining the efficacy of a sterilization process.